1. Field of the Invention
The present invention relates to a method for processing print jobs by an image-processing apparatus comprising an output module for receiving an output of the print jobs and a control unit configured to maintain a queue of print jobs to be processed. The method comprises for each print job the steps of printing the print job by the image-processing apparatus and stacking the output of the print job in the output module,
2. Background of the Invention
A method for processing print jobs on a printer has, for example, been disclosed by U.S. Pat. No. 6,681,245. The method disclosed in this patent is suitable for printing documents from a user workstation and comprises detecting of normal and special events which are related to the printer, a printer server, a job or a user operation. These events are presented in a log file. The method is directed to printing of jobs with user interaction. Since all kind of events are registered, the log file becomes large. Since the log file is usually ordered by time of occurrence of the event, the entries of a certain kind of event are scattered among the entries of the log file. If the event is not related to a print job, it becomes difficult to trace the print job corresponding to the event. Therefore the log file is not suited to get a quick overview of a certain kind of event or to trace a faulty print job.
When printing documents on an image-processing apparatus, a print error may occur. For example, a document may be printed erroneously. Also, the image-processing apparatus may stop due to the error and the user will, for example, find a faulty document in the output module of the image-processing apparatus. This finding may be easy since this faulty document is the last document printed by the image-processing apparatus.
However, a document may be printed erroneously and not lead to a stop of the image-processing apparatus. A print error of this kind may lead to a fault in the output of the document, and even to no output at all. When the image-processing apparatus has continued printing jobs from the queue after such a faulty job, such an error is called a machine recoverable error or a non-fatal error. Such a faulty job may have several causes, e.g. a wrong page format of the source file of the document, extra pages due to error recovery actions of the image-processing apparatus, an out-of-range value of a sensor of the image-processing apparatus or an out-of-memory problem of the image-processing apparatus. Especially when printing many documents, without user intervention, a machine recoverable error may occur and may cause a job to be printed erroneously. However, the job is nevertheless received by the output module and completed. Jobs, subsequent to the faulty job, are printed such that the faulty output of the faulty job is in the output module among all the documents printed. In view of this, it can become difficult to locate the faulty output.
An error may occur, which can only be handled by operator intervention. Such an error is called an operator recoverable error. An example of an operator recoverable error is a paper jam in the image-processing apparatus. If such an error occurs, the operator has to open doors of the image-processing apparatus, remove paper and close the doors again, and so on. If the operator has not interfered with the documents in the output module, the print job which has caused the paper jam has been completed and the output of the print job has been stacked in the output module of the image-processing apparatus. However, the output of the print job may nevertheless contain a fault.
The processing of the jobs described in this application is directed to let the image-processing apparatus print jobs from the queue continuously. If a print job can not be completed or an abnormal end of the job has occurred in the case of a machine recoverable error or an operator recoverable error, the image-processing apparatus will not stop, but will go on with the next print job in the queue. Hereinafter, a machine recoverable error and an operator recoverable error are both referred to as a recoverable error.
It is noted that U.S. Patent Application Publication No. 2003/112452 discloses event log files created by an image-processing apparatus. Transmittal errors of the print job to the printer and converting errors making a print ready file corrupt are logged and result in a general error message at the apparatus and a stop of the processing of the apparatus. The job will not be executed and will generate no output. The event log also contains errors due to a printer function in the image-processing apparatus. Information not related to a print job, but to a printer function that is selected by a user, is tracked, such as the usage of a printer mechanical component like a collator or a stapler. From such an event log, the position of faulty pages in a stacked output due to a printer function error is not clear. Moreover, such an event log includes a great number of entries of different kinds, and it is difficult or at least time-consuming to extract information related to possible incorrectly printed sheets in an output stack.
An abnormal end of the job may be that the print job is not translated by the image-processing apparatus in an output that was expected by the user. Sometimes user files are corrupted or in a format that is not supported by the image-processing apparatus. The image-processing apparatus is then not able to process the input of the print job correctly, or problems are encountered during processing of the image data of the print job. This may result in a missing page of a document to be printed or may result in no output at all. In other words, all pages of the document are missing. In some situations an additional page may be printed. This may be the case, for example, if the image-processing apparatus is provided with an error recovery mechanism that detects a faulty page and triggers the image-processing apparatus to print an extra page behind the faulty page, which extra page does not contain the error of the faulty page.
A user sends a job or a plurality of jobs to the image-processing apparatus. The user may walk up to the image-processing apparatus and arrive at the image-processing apparatus after all jobs have been processed. The user may then look at the user interface and investigate the event logging, which has been generated by the image-processing apparatus. The user may conclude from the logging that during processing the plurality of print jobs some error has occurred, but the user cannot immediately determine which job is responsible for the error, which job has not been completed successfully and/or which job has been completed with an abnormal end. The faulty job output is often submerged into a stack of printed documents of a plurality of jobs. Sometimes the image-processing apparatus is provided with a separate output module for a faulty job, and then the user may check this separate output module for the faulty output. However, if the image-processing apparatus is not provided with such a separate output module, the faulty output may be difficult to find in the regular output module. This is especially the case when printing wide format documents, since most wide format printers are not provided with such a separate output module.
In most cases, for example, when printing is done unattended, the number of printed documents may be large, which results in a large pile of documents in the output module of the image-processing apparatus. For example in overnight printing without the possibility of any operator intervention, if the printing has not stopped, the operator will find a stack of printed documents in the morning. To reveal if a document has been printed incompletely or over-completely as described here-above, a glance at the stack of the documents is not sufficient. The operator has to look at the documents one by one or consult the log file, both ways of working being rather cumbersome.